1. Field of the Invention
The present invention relates to the shipping and transportation of goods in containers by truck. More particularly, the present invention relates to an adjustable truck trailer chassis that may accommodate shipping containers of various lengths.
2. Description of the Prior Art
The use of shipping containers has revolutionized the transport of freight. Goods are now placed in standardized shipping containers and transported from an origin point to a destination point by any of the common commercial transport means, such as ship, rail, or truck. In the course of transit, the containers can be carried by any combination of these transport means. Thus, a container may be routed from a factory to a train terminal or shipping dock by truck, removed from the truck and placed on a railroad flatcar or into a ship's cargo hold, transported to a destination point, and then placed on another truck for distribution.
To transport containers by truck is a simple matter of placing a container onto an appropriate container chassis and securing the container to the chassis by means of industry standard locking bolts. Because the containers are readily fastened to and removed from a truck chassis, handling is fast, efficient, and inexpensive. A further advantage of containers, as opposed to open packaging, such as pallets and boxes, is that valuable goods securely packed in a container are not subject to excessive handling, which may damage the goods. Sealing the containers at point of origin significantly reduces pilferage, vandalism, or theft of the goods contained therein.
Shipping containers are generally available in various sizes from 20-48 feet in length. For transport by truck, each container requires a container chassis of corresponding length. Thus, a 20-foot container requires a 20-foot chassis, a 23-foot container requires a 23-foot chassis, and so on. For a trucking concern to handle all sizes of containers, it is necessary that the concern maintain an inventory of chassis corresponding to the commonly used containers. The chassis inventory is often idle because at any given time, the distribution of various lengths of containers transported to various lengths of chassis in inventory does not bear a one-to-one correspondence. As a result, a moderately expensive capital asset (the chassis) lies idle a portion of the time.
Another problem with prior art container chassis occurs when a trucking concern must accommodate large shipments of several containers having the same size. The trucking concern may maintain a limited inventory of any particular chassis size. Large shipments of one size of containers may readily exhaust this inventory, resulting in lost business due to the concern's inability to accommodate the entire shipment of containers.
Finally, it is desirable to pick up additional containers at or near the point of delivery of a previous container load. Thus, the return chassis trip becomes a profit generating trip rather than an idle equipment return trip. Unfortunately, the return load may not be a container of the same size as that delivered with the non-empty chassis. Thus, an empty chassis of the proper size must be sent to fetch the container while an idle empty chassis of the wrong size is returned to the trucking concern's yard or facility. This is a significant waste of the concern's capital equipment resources and personnel time.
Larger containers, such as those of 40 feet in length, require a very large container chassis. Handling such chassis in congested urban traffic is slow, tedious, and fraught with peril. Returning an empty 40-foot chassis is just as difficult as handling a loaded 40-foot chassis. Actually, an empty chassis is even more difficult to handle because the driver cannot readily see the back end of the chassis as well in the absence of a container thereon.